While attending a large exhibition or a convention, or visiting a shopping mall, a visitor or a customer needs a hand-held shopping bag to carry out materials such as advertising documents or purchased items. But when the materials have been accumulated in the shopping bag, it is not convenient for the visitor or the customer to carry the shopping bag. Thus, there is a need for a shopping bag which is not only convenient but also labor-saving. For this purpose, attempts to design such a shopping bag have been made in the past. For example, U.S. Pat. No. 6,293,569 has disclosed a mobile shopping bag assembly that is distinct from conventional bag carriers. Although this kind of bag can address the problem by means of wheel assembly mounted at the bottom of the bag and is labor saving, such a bag still suffers from the drawbacks below:
(1) the wheels assembly requires to puncture through the bottom end of the bag, which inevitably cause a damage to the integrity of the bag body;
(2) the assembly needs a platform insert made of plastic material to be placed in the bag, but a complicated injection molding process is required to form the platform insert, and therefore would be a difficulty for mass production in terms of production time and cost; and
(3) it takes long time to assemble the bag of this patent because one can only insert one wheel at a time, while this bag is designed to have as many as 4 castor wheels.
As a result, the shopping bag assembly disclosed in U.S. Pat. No. 6,293,569 may be commercially undesirable.
U.S. patent application Ser. No. 12/055,394 was filed by the present applicant to claim a shopping bag with a detachable wheel chassis, which comprises a bag body having bag handles and a wheel chassis connected with the shopping bag body in an inserting manner. Said wheel chassis includes a shaft, two wheels rotatably mounted on two ends of the shaft by means of fixing elements, and a supporting assembly arranged on the shaft including a supporting rod, two convex supporting members and a bracket. This shopping bag is characterized by the fact that the bag body is provided with a receiving portion on its bottom and an inserting element detachably disposed in the receiving portion of the bag body. Although this bag is satisfactory to a great extent, it still has drawbacks that the entire structure of the wheel chassis is somewhat complicated, and the inserting element and the bracket need to be fastened by an additional soldering process. In addition, the wheel chassis is adapted to limited types of shopping bags only, because the change of the inserting element cannot be effected.
There is a need for simplifying the wheel chassis and eliminating the need of soldering process. A new shopping bag has been developed which is low in cost, convenient to use and simple in configuration.